package com.huawei;

import java.util.Scanner;

/**
 * Created by Z-hong on 2024/7/2.
 */

public class HJ10 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        String str=sc.nextLine();
        char arr[]=str.toCharArray();
        int flag[] = new int[128];
        for (char c : arr) {
            flag[(int)c] = 1;
        }
        int count=0;
        for (int i : flag) {
            if(i == 1) count++;
        }
        System.out.println(count);
    }
}
